Despite the widespread use of the 5-HT3 receptor antagonist antiemetics, ondansetron (Zofran®, Glaxo Wellcome Oncology/HIV, Research Triangle Park, N.C.) in 1991, granistron (Kytril,® SmithKline Beecham Pharmaceuticals, Philadelphia, Pa.) in 1994, and dolasetron mesylate (Anzemet,® Hoechst Marion Roussel, Kansas City, Mo.), post-chemotherapy nausea and vomiting continue to be reported by up to 70% of patients receiving highly emetogenic chemotherapy agents, such as cisplatin, carboplatin and doxorubicin. Research also suggests that the 5-HT3 receptor antagonists are clinically more effective against emesis than they are against nausea.
Delayed post-chemotherapy nausea is a particularly difficult problem as it does not develop until after the patient has left the treatment location and is not well-controlled by currently available antiemetics. Data from a recently completed URCC CCOP Research Base study of patients receiving cisplatin, carboplatin or doxorubicin indicates that although nausea from receipt of these drugs is most likely to develop within the first 48 hours after administration of chemotherapy, in 18% of the patients it was first reported on or after Day 3 of the cycle.
Patients who suffer from post-chemotherapy nausea may also develop symptoms in anticipation of treatment. Anticipatory nausea (AN) is reported by approximately 20% of patients at any one chemotherapy cycle and by 25-30% of patients by the fourth chemotherapy cycle. Anticipatory vomiting (AV) develops in 8-20% of patients. No pharmacologic agents have had success in treating AN once it has occurred, and, although the behavioral method of systematic desensitization can be effective, it is not readily available in most clinic settings.
All in all, there is still a great deal of room for improvement in the control of nausea and vomiting (NV) associated with chemotherapy for cancer. Furthermore, antiemetics currently in widespread use have been associated with significant adverse effects, such as sedation, extra-pyramidal side effects and hypotension (associated with dopamine antagonists), as well as headache, diarrhea or constipation (associated with 5-HT3 receptor antagonists). A desirable attribute in any substitute or additional antiemetic medication would be the absence of clinically significant adverse effects.